testrunner: Added argument for a clean only run.
testrunner: Added argument for a clean only run.

mnordsletten/IncludeOS,AndreasAakesson/IncludeOS,ingve/IncludeOS,ingve/IncludeOS,alfred-bratterud/IncludeOS,AndreasAakesson/IncludeOS,AnnikaH/IncludeOS,mnordsletten/IncludeOS,mnordsletten/IncludeOS,mnordsletten/IncludeOS,hioa-cs/IncludeOS,alfred-bratterud/IncludeOS,AnnikaH/IncludeOS,hioa-cs/IncludeOS,AnnikaH/IncludeOS,ingve/IncludeOS,hioa-cs/IncludeOS,AndreasAakesson/IncludeOS,AnnikaH/IncludeOS,mnordsletten/IncludeOS,alfred-bratterud/IncludeOS,alfred-bratterud/IncludeOS,alfred-bratterud/IncludeOS,AndreasAakesson/IncludeOS,AndreasAakesson/IncludeOS,mnordsletten/IncludeOS,AndreasAakesson/IncludeOS,ingve/IncludeOS,hioa-cs/IncludeOS,AnnikaH/IncludeOS,hioa-cs/IncludeOS,ingve/IncludeOS